As described above, this invention related to the production of cis-1-chloro-3,3,3-trifluoropropene, which may be designated as HCFO-1233zd (Z), 1233zd(Z), or cis-1233zd. The preferred designation used herein is 1233zd(Z). 1233zd (Z) is a low global warming compound that has applications as a replacement for high global warming materials, for example in foam blowing and aerosol propellant applications.
The isomeric compounds 1233zd may be produced by a number of different methods. Examples include the dehydrochlorination of CF3CH2CHCl2 (J. Am. Chem. Soc., 64 (1942) 1157-9); the dehydrofluorination of 3-chloro-1,1,1,3-tetrafluoropropane (U.S. Pat. No. 7,829,747); and the fluorination of halogenated propanes (U.S. Pat. Nos. 5,710,352, 6,111,150, and 6,844,475). Other methods are shown in U.S. Pat. Nos. 6,958,424 and 5,616,819. See also U.S. Patent Pub. No. 2008/0103342 and PCT Pub. No. WO 2010/059496). In most reactions the trans-isomer of 1233zd is the thermal dynamically favored product, with typically only about 3% to 5% of cis-isomer obtained in most manufacturing processes.
PCT Pub. No. WO 2010/068715 provides a process in which the trans-isomer of 1233zd can be isomerized over a fluorinated Cr2O3 catalyst in the vapor phase at a temperature of about 300° C. The resulting amount of the cis-isomer is only about 10%, combined with from about 2% to 3% of other materials. This process thus requires multiple repeated cycles in order to generate large quantities of the desired cis-isomer of 1233zd.
U.S. Patent Pub. No. U.S. 2012-0215041 A1 (Ser. No. 13/030,789) describes a process for the reduction 1-chloro-3,3,3-trifluoropropyne with palladium under hydrogen atmosphere to stereospecifically generate cis-1233zd in 53% yield. However, unless the reduction process is carefully controlled, over reduction can occur, which leads to the compounds CF3CH═CH2 and CF3CH2CH3.
Both the cis (or Z) isomer and the trans (or E) isomer of 1233zd have practical applications. The cis-isomer of HCFO-1233zd is more suitable for solvent applications than the trans isomer because of a higher boiling point.
U.S. Pat. No. 6,362,383 teaches a process for preparing 1,1,1,3,3-pentafluoro-propane (HFC-245fa) by (1) a first reaction step in which 1,1,1,3,3-pentachloropropane (HCC-240fa) is reacted with hydrogen fluoride in the liquid phase in the presence of a first hydrofluorination catalyst under conditions that are suitable for obtaining a mixture of reaction products comprising 1-chloro-3,3,3-trifluoropropene (HCFO-1233zd) in substantial amount, and (2) a second reaction step in which the 1-chloro-3,3,3-trifluoropropene (HCFO-1233zd) obtained from the first step is reacted with hydrogen fluoride in the liquid phase in the presence of a second hydrofluorination catalyst, and preferably while hydrogen chloride is continuously fed in, in order to obtain 1,1,1,3,3-pentafluoro-propane (HFC-245fa).
The disclosures of the foregoing references are hereby incorporated herein by reference.
Thus there remains a need for a process which makes 1233zd wherein a substantial portion of cis isomer is present or even more preferably, wherein the process stereospecifically produces the cis-isomer of 1233zd.